1. Field of the invention
The present invention relates to novel piperidyltriazine derivatives which are useful for improving the stability to light, heat and oxidation of polymeric substances.
2. Description of the prior art
It is known that synthetic polymers are liable to undergo a severe deterioration of their physical and chemical properties when they are exposed to sunlight or other ultraviolet light source.
In order to improve the stability to light of said synthetic polymers, various stabilizers have been proposed, some of which have found a wide commercial acceptance in the field, such as some benzophenones, benzotriazoles, aromatic salicylates, .alpha.-cyanoacrylic acid esters, organo-tin compounds and the like, which although having a certain efficiency level, are not successful to solve the problem completely.
It is further known that some piperidine derivatives of 1,3,5-triazine can be used to protect a polymeric material from degradation due to ultraviolet light.
In particular, French patent 2181 059 describes triazine compounds having the general formula ##STR1## wherein Z', Z", Z"' can be, among others, piperidine radicals of type ##STR2## in which X is --O-- or --NH--.
The above products considerably improve the light stability of polyolefins, but they are of poor utility in the application to an article of small thickness, such as fibers and films, inasmuch as they tend to be extracted by contact with water or aqueous solutions of surfactants, the stabilizer amount remaining in the polymer being no longer sufficient to provide the required light stabilization.
On the other hand the usual commercial light stabilizers, such as benzophenone derivatives, have a reduced effect on light stabilization in polyolefins, when used in articles of small thickness, such as fibers and films.
Therefore there is a need of more efficient light stabilizers for the protection against the polymer degradation due to UV light, as well as stabilizers fast to extraction from the polymer.